<!DOCTYPE html>
<html>
<body>

<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">
Your browser does not support the HTML5 canvas tag.</canvas>

<script type="text/javascript">

var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.fillStyle="#0000ff";
ctx.fillRect(20,20,150,100);

</script>

</body>
</html>